A compound with cyanopyridine as the core and its application

Abstract

The present invention relates to a compound with a cyanopyridine as the core and its application, belonging to the field of semiconductor technology. The structure of the compound provided by the present invention is shown in the general formula (1), wherein, among R1-R5, 1 represents a cyano group, 3 are the same or different and represent a substituted or unsubstituted carbazolyl group, and 1 represents a substituted or unsubstituted C6-C 30 aryl group, a substituted or unsubstituted C3-C 30 heteroaryl group; and among R1-R5, there are exactly 3 that are the same or different and represent a substituted or unsubstituted carbazolyl group. When the compound of the present invention is used as a light-emitting layer material of an OLED light-emitting device, it can produce a TADF effect, effectively reduce the voltage of the device, improve the light-emitting efficiency of the device, and extend the lifespan of the device.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and more particularly to a compound with cyanopyridine as the core and its applications. Background Art

[0002] Organic light-emitting diode (OLED) device technology can be used to manufacture new display products and new lighting products, and is expected to replace existing liquid crystal displays and fluorescent lamp lighting, with broad application prospects. The OLED light-emitting device has a sandwich-like structure, including electrode material film layers and organic functional materials sandwiched between different electrode material film layers. Various different organic functional materials are stacked together according to their uses to jointly form an OLED light-emitting device. As a current device, when a voltage is applied to the two electrodes of the OLED light-emitting device, positive and negative charges in the organic layer functional material film layer act through an electric field, and the positive and negative charges further recombine in the light-emitting layer, thereby generating OLED electroluminescence.

[0003] The development and use of the light-emitting layer materials of OLEDs have gone through three main stages. The first stage is mainly based on the fluorescence emission mechanism, the second stage is mainly based on the phosphorescence emission mechanism, and the third stage uses TADF materials as the light-emitting layer materials, effectively utilizing triplet excitons to improve the light-emitting efficiency of the device. Developed to date, TADF materials have extensive applications in the light-emitting layer, and their structures are controllable, their properties are stable, and their prices are cheap without the need for precious metals, with broad application prospects in the field of OLEDs.

[0004] Theoretically, TADF materials can achieve 100% exciton utilization through reverse intersystem crossing from the triplet state to the singlet state. However, in actual applications as the host or dopant, the device performance is not good, and there are still the following main problems: Due to the design requirements of TADF materials for a small S1-T1 band gap, it is difficult to achieve both a fast reverse intersystem crossing rate (short delayed luminescence lifetime) and a high fluorescence quantum yield. Summary of the Invention

[0005] In view of the above problems existing in the prior art, the present invention provides a compound with cyanopyridine as the core and its applications. The compound of the present invention contains a specific cyanide group and a carbazole-substituted pyridine structure, so that the compound of the present invention has a short delayed luminescence lifetime and a high fluorescence quantum yield, thereby effectively improving the efficiency and lifetime of OLED devices.

[0006] The technical solution of the present invention is as follows:

[0007] A compound with cyanopyridine as the core, the structure of the compound is shown in the general formula (1):

[0008]

[0009] In general formula (1), one of R1 - R5 represents a cyano group, three of them, which are the same or different, represent a substituted or unsubstituted carbazolyl group, and one of them represents a substituted or unsubstituted C6 - C 30 aryl group, a substituted or unsubstituted C3 - C 30 heteroaryl group; and among R1 - R5, there are exactly three, which are the same or different, representing a substituted or unsubstituted carbazolyl group;

[0010] The substituents for the substitution groups are each independently selected from a halogen atom, a deuterium atom, a cyano group, a trifluoromethyl group, a C1 - C 10 alkyl group, a C3 - C 20 cycloalkyl group, a C6 - C 30 aryl group, a C3 - C 30 heteroaryl group, or a combination of one or more of them;

[0011] The heteroatoms in the heteroaryl group are each independently selected from one or more of oxygen, sulfur, and nitrogen.

[0012] In a preferred embodiment, R2 represents a cyano group, and R3 represents a substituted or unsubstituted C6 - C 30 aryl group, a substituted or unsubstituted C3 - C 30 heteroaryl group, and R1, R4, and R5 each independently represent a substituted or unsubstituted carbazolyl group; or R2 represents a cyano group, and R1 represents a substituted or unsubstituted C6 - C 30 aryl group, a substituted or unsubstituted C3 - C 30 heteroaryl group, and R3, R4, and R5 each independently represent a substituted or unsubstituted carbazolyl group.

[0013] In a preferred embodiment, R1 represents a cyano group, and R2 represents a substituted or unsubstituted C6 - C 30 aryl group, a substituted or unsubstituted C3 - C 30 heteroaryl group, and R3, R4, and R5 each independently represent a substituted or unsubstituted carbazolyl group; or R1 represents a cyano group, and R3 represents a substituted or unsubstituted C6 - C 30 aryl group, a substituted or unsubstituted C3 - C 30 heteroaryl group, and R2, R4, and R5 each independently represent a substituted or unsubstituted carbazolyl group.

[0014] In a preferred embodiment, R3 represents a cyano group, and R1 represents a substituted or unsubstituted C6 - C 30 aryl group, a substituted or unsubstituted C3 - C 30One of the heteroaryls, R2, R4, and R5 are the same or different and each represents a substituted or unsubstituted carbazolyl group; or, R3 represents a cyano group and R2 represents a substituted or unsubstituted C6-C 30 aryl group, a substituted or unsubstituted C3-C 30 One of the heteroaryls, R1, R4, and R5 are the same or different and each represents a substituted or unsubstituted carbazolyl group.

[0015] More preferably, the substituted or unsubstituted C6-C 30 aryl group is one of a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, a substituted or unsubstituted terphenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted phenanthryl group, a substituted or unsubstituted 9,9-dimethylfluorenyl group, a substituted or unsubstituted 9,9-diphenylfluorenyl group;

[0016] The substituted or unsubstituted C3-C 30 heteroaryl group is one of a substituted or unsubstituted pyridyl group, a substituted or unsubstituted pyrimidinyl group, a substituted or unsubstituted pyridazinyl group, a substituted or unsubstituted pyrazinyl group, a substituted or unsubstituted quinolinyl group, a substituted or unsubstituted triazinyl group, a substituted or unsubstituted N-phenylcarbazolyl group, a substituted or unsubstituted dibenzofuranyl group, a substituted or unsubstituted dibenzothiophenyl group;

[0017] The substituents for the substituting groups are each independently selected from one or more of a halogen atom, a deuterium atom, a cyano group, a trifluoromethyl group, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tert-butyl group, a pentyl group, a cyclohexyl group, a heptyl group, an adamantyl group, a phenyl group, a biphenyl group, a naphthyl group, a pyridazinyl group, a pyrazinyl group, a triazinyl group, a pyrimidinyl group, a pyridyl group, a dibenzofuranyl group, a carbazolyl group, a dibenzothiophenyl group.

[0018] The specific structure of the compound is any one of the following structures:

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027] An organic electroluminescent device includes an anode and a cathode, and an organic light-emitting functional layer therebetween. The organic light-emitting functional layer contains the compound with cyanopyridine as the core.

[0028] The organic light-emitting functional layer includes a light-emitting layer, and the light-emitting layer contains the compound with cyanopyridine as the core. The light-emitting layer includes a first host material, a second host material, and a doping material. The first host material is a TADF material, and the second host material is the compound with cyanopyridine as the core.

[0029] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0030] The compound of the present invention contains a cyano group and three carbazole-substituted pyridine structures, and has efficient TADF characteristics. When the material of the present invention is used as a host material, the triplet energy can be fully utilized to improve the light-emitting efficiency of the device; it has a short delay lifetime, the triplet excitons have a short existence time, effectively reducing the triplet exciton quenching of the host material and prolonging the lifetime of the device; it has a high fluorescence quantum yield. When the material of the present invention is used as a sensitizer, the efficiency of the device can be effectively improved. Description of the Drawings

[0031] Figure 1 It is a schematic structural diagram of the compound of the present invention applied to an OLED device;

[0032] Among them, 1 is a transparent substrate layer, 2 is an anode layer, 3 is a hole injection layer, 4 is a hole transport layer, 5 is an electron blocking layer, 6 is a light-emitting layer, 7 is a hole blocking layer, 8 is an electron transport layer, 9 is an electron injection layer, and 10 is a cathode layer. Detailed Embodiments

[0033] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments and the drawings. Without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The present invention will be further described below in conjunction with the drawings and specific embodiments, but it is not a limitation of the present invention.

[0034] In the present invention, unless otherwise specified, HOMO means the highest occupied molecular orbital, and LUMO means the lowest unoccupied molecular orbital. In addition, in the present invention, the HOMO and LUMO energy levels are represented by absolute values, and the comparison between the energy levels is also a comparison of the absolute values. Those skilled in the art know that the larger the absolute value of the energy level, the lower the energy of the energy level.

[0035] Any numerical range recited herein is intended to include all sub-ranges having the same numerical precision that fall within the recited range. For example, "1.0 to 10.0" is intended to include all sub-ranges between the recited minimum value of 1.0 and the recited maximum value of 10.0 (and including 1.0 and 10.0), that is, all sub-ranges having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0. Any maximum numerical limitation recited herein is intended to include all smaller numerical limitations incorporated herein, and any minimum numerical limitation recited herein is intended to include all larger numerical limitations incorporated herein. Accordingly, the applicant reserves the right to amend the present specification, including the claims, to expressly describe any sub-ranges that fall within the ranges expressly described herein.

[0036] In the drawings, for the sake of clarity, the dimensions of layers and regions may be exaggerated. It will also be understood that when a layer or element is referred to as being "on" another layer or substrate, the layer or element may be directly on the other layer or substrate, or intervening layers may be present. Further, it will be understood that when a layer is referred to as being "between" two layers, the layer may be the only layer between the two layers, or one or more intervening layers may be present. Like reference numerals throughout the specification denote like elements.

[0037] In the present invention, when describing electrodes, organic electroluminescent devices, and other structures, terms indicating orientation such as "upper", "lower", "top", and "bottom" only represent the orientation in a specific state, and do not mean that the relevant structures can only exist in the stated orientation; on the contrary, if the structure can be repositioned, for example, inverted, the orientation of the structure will be changed accordingly. Specifically, in the present invention, the "bottom" and "lower" sides of the electrode refer to the side of the electrode that is close to the substrate during the preparation process, and the opposite side away from the substrate is the "top" and "upper" sides.

[0038] In the present specification, "aryl" refers to a group having at least one aromatic hydrocarbon moiety and the aromatic hydrocarbon moiety is generally connected through a single bond and a non-aromatic fused ring containing directly or indirectly fused aromatic hydrocarbon moieties. The aryl group can be a monocyclic, polycyclic, or fused polycyclic (i.e., rings sharing adjacent pairs of carbon atoms) functional group.

[0039] In the present specification, "heteroaryl" includes a cyclic group containing at least one heteroatom selected from N, O, and S instead of carbon (C) of a cyclic compound, such as aryl, cycloalkyl, fused ring, or a combination thereof. When the heterocyclic group is a fused ring, each ring or all rings of the heteroaryl group may contain at least one heteroatom.

[0040] More precisely, substituted or unsubstituted C6-C 30 aryl and / or substituted or unsubstituted C3-C 30Heteroaryl refers to substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted anthryl, substituted or unsubstituted phenanthryl, substituted or unsubstituted condensed tetraphenyl, substituted or unsubstituted pyrenyl, substituted or unsubstituted biphenyl, substituted or unsubstituted p-terphenyl, substituted or unsubstituted m-terphenyl, substituted or unsubstituted group, substituted or unsubstituted dianthryl, substituted or unsubstituted perylenyl, substituted or unsubstituted indenyl, substituted or unsubstituted furyl, substituted or unsubstituted thienyl, substituted or unsubstituted pyrrolyl, substituted or unsubstituted pyrazolyl, substituted or unsubstituted imidazolyl, substituted or unsubstituted triazolyl, substituted or unsubstituted oxazolyl, substituted or unsubstituted thiazolyl, substituted or unsubstituted oxadiazolyl, substituted or unsubstituted thiadiazolyl, substituted or unsubstituted pyridyl, substituted or unsubstituted pyrimidinyl, substituted or unsubstituted pyrazinyl, substituted or unsubstituted pyridyl, substituted or unsubstituted benzofuryl, substituted or unsubstituted benzothienyl, substituted or unsubstituted benzimidazolyl, substituted or unsubstituted indolyl, substituted or unsubstituted quinolinyl, substituted or unsubstituted isoquinolinyl, substituted or unsubstituted quinazolinyl, substituted or unsubstituted quinoxalinyl, substituted or unsubstituted naphthyridinyl, substituted or unsubstituted benzoxazinyl, substituted or unsubstituted benzothiazinyl, substituted or unsubstituted acridinyl, substituted or unsubstituted phenazinyl, substituted or unsubstituted phenothiazinyl, substituted or unsubstituted phenoxazinyl, substituted or unsubstituted fluoranthenyl, substituted or unsubstituted dibenzofuryl, substituted or unsubstituted dibenzothienyl, substituted or unsubstituted carbazolyl, combinations thereof or fused rings of combinations of the foregoing groups, but not limited thereto.

[0041] The C1-C 10 alkyl (including straight-chain alkyl and branched-chain alkyl) refers to methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, isobutyl, sec-butyl, neopentyl, n-pentyl, isopentyl, octyl, heptyl, n-decyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 1-butylpentyl, etc., but not limited thereto.

[0042] The halogen atom in the present invention refers to a chlorine atom, a fluorine atom or a bromine atom, etc., but not limited thereto.

[0043] The C3-C 20 Cycloalkyl refers to a monovalent monocyclic saturated hydrocarbon group including 3 to 20 carbon atoms as ring-forming atoms. In this article, C4-C9 cycloalkyl is preferably used, more preferably C5-C8 cycloalkyl, and particularly preferably C5-C7 cycloalkyl. Non-limiting examples thereof may include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, 4,4-dimethylcyclohexyl, adamantyl and cycloheptyl.

[0044] Organic electroluminescent device

[0045] The present invention provides an organic electroluminescent device, comprising an anode and a cathode, and an organic light-emitting functional layer therebetween, wherein the organic light-emitting functional layer contains the compound with cyanopyridine as the core.

[0046] In a preferred embodiment of the present invention, the organic light-emitting functional layer includes a light-emitting layer, and the light-emitting layer contains the compound with cyanopyridine as the core.

[0047] In a preferred embodiment of the present invention, the light-emitting layer comprises a first host material, a second host material and a doping material, wherein the first host material is a TADF material and the second host material is the compound with cyanopyridine as the core.

[0048] Figure 1 It is a schematic structural diagram of the application of the compound of the present invention in an OLED device. Among them, 1 is a transparent substrate layer, 2 is an anode layer, 3 is a hole injection layer, 4 is a hole transport layer, 5 is an electron blocking layer, 6 is a light-emitting layer, 7 is a hole blocking layer, 8 is an electron transport layer, 9 is an electron injection layer, and 10 is a cathode layer.

[0049] As the substrate of the organic electroluminescent device of the present invention, any substrate commonly used in organic electroluminescent devices can be used. Examples are transparent substrates such as glass or transparent plastic substrates; opaque substrates such as silicon substrates; flexible PI film substrates. Different substrates have different mechanical strengths, thermal stabilities, transparencies, surface smoothnesses, and water resistances. Depending on the nature of the substrate, its usage directions are different. In the present invention, a transparent substrate is preferably used. The thickness of the substrate is not particularly limited.

[0050] A first electrode is formed on the substrate, and the first electrode and the second electrode can face each other. The first electrode can be an anode. The first electrode can be a transmissive electrode, a semi-transmissive electrode or a reflective electrode. When the first electrode is a transmissive electrode, it can be formed using a transparent metal oxide, such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO) or indium tin zinc oxide (ITZO), etc. When the first electrode is a semi-transmissive electrode or a reflective electrode, it can include Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr or a metal mixture. The thickness of the first electrode layer depends on the material used and is usually 50 - 500 nm, preferably 70 - 300 nm and more preferably 100 - 200 nm.

[0051] The organic light-emitting functional layer disposed between the first electrode and the second electrode sequentially includes a hole transport region, a light-emitting layer and an electron transport region from bottom to top.

[0052] In this article, examples of the hole transport region constituting the organic electroluminescent device can include a hole injection layer, a hole transport layer, an electron blocking layer, etc.

[0053] As the materials for the hole injection layer, hole transport layer, and electron blocking layer, any material can be selected from known related materials for OLED devices for use.

[0054] Examples of the above materials may be phthalocyanine derivatives, triazole derivatives, triarylmethane derivatives, triarylamine derivatives, oxazole derivatives, oxadiazole derivatives, hydrazone derivatives, stilbene derivatives, pyridinoline derivatives, polysilane derivatives, imidazole derivatives, phenylenediamine derivatives, amino-substituted quinone derivatives, styryl anthracene derivatives, styrylamine derivatives and other styrene compounds, fluorene derivatives, spirofluorene derivatives, silazane derivatives, aniline copolymers, porphyrin compounds, carbazole derivatives, polyarylalkane derivatives, polyphenylene vinylenes and their derivatives, polythiophenes and their derivatives, poly-N-vinylcarbazole derivatives, thiophene oligomers and other conductive polymer oligomers, aromatic tertiary amine compounds, styrylamine compounds, triamines, tetraamines, benzidine compounds, propynediamine derivatives, p-phenylenediamine derivatives, m-phenylenediamine derivatives, 1,1'-bis(4-diarylaminophenyl)cyclohexane, 4,4'-bis(diarylamino)biphenyls, bis[4-(diarylamino)phenyl]methanes, 4,4'-bis(diarylamino)terphenyls, 4,4'-bis(diarylamino)tetraphenyls, 4,4'-bis(diarylamino)diphenyl ethers, 4,4'-bis(diarylamino)diphenyl sulfides, bis[4-(diarylamino)phenyl]dimethylmethanes, bis[4-(diarylamino)phenyl]-bis(trifluoromethyl)methanes, or 2,2-diphenylethylene compounds, etc.

[0055] Furthermore, according to the device matching requirements, the hole transport film layer between the hole transport auxiliary layer and the hole injection layer that constitutes the organic electroluminescent device can be a single film layer or a stacked structure of multiple hole transport materials. In this article, for the above-mentioned hole carrier conduction film layers with different functions, their film thicknesses are not particularly limited.

[0056] The hole injection layer contains a host organic material that can conduct holes, and also contains a P-type doping material with a deep HOMO energy level (the corresponding LUMO energy level will also be very deep). Based on empirical summaries, in order to achieve smooth injection of holes from the anode to the organic film layer, the HOMO energy level of the host organic material that conducts holes used in the anode interface buffer layer must have certain characteristics with the P-doping material, so as to expect the occurrence of a charge transfer state between the host material and the doping material, achieve Ohmic contact between the buffer layer and the anode, and achieve efficient injection from the electrode to hole injection conduction.

[0057] In view of the above empirical summary, for hole-type host materials with different HOMO energy levels, different P-doping materials need to be selected to match them in order to achieve ohmic contact at the interface and improve the hole injection effect.

[0058] Therefore, in an embodiment of the present invention, in order to better inject holes, the hole injection layer further comprises a charge-conductive P-type doping material selected from the following: quinone derivatives such as tetracyanoquinodimethane (TCNQ) and 2,3,5,6-tetrafluoro-tetracyano-1,4-benzoquinodimethane (F4-TCNQ); or hexaazatriphenylene derivatives such as 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HAT-CN); or cyclopropane derivatives such as 4,4',4”-((1E,1'E,1”E)-cyclopropane-1,2,3-trimethylenetris(cyanomethylidene))tris(2,3,5,6-tetrafluorobenzyl); or metal oxides such as tungsten oxide and molybdenum oxide, but not limited thereto.

[0059] In the hole injection layer of the present invention, the ratio of the hole transport material to the P-type doping material used is 99:1 - 95:5, preferably 99:1 - 97:3, based on mass.

[0060] The thickness of the hole injection layer of the present invention can be 5 - 100 nm, preferably 5 - 50 nm and more preferably 5 - 20 nm, but the thickness is not limited to this range.

[0061] The thickness of the hole transport layer of the present invention can be 5 - 200 nm, preferably 10 - 150 nm and more preferably 20 - 100 nm, but the thickness is not limited to this range.

[0062] The thickness of the electron blocking layer of the present invention can be 1 - 20 nm, preferably 5 - 10 nm, but the thickness is not limited to this range.

[0063] After forming the hole injection layer, the hole transport layer and the electron blocking layer, a corresponding light-emitting layer is formed on the electron blocking layer.

[0064] The light-emitting layer may comprise a host material and a guest material, and the host material uses the organic compound with a pyridine derivative as the core of the present invention.

[0065] In the light-emitting layer of the present invention, the ratio of the host material to the guest material used is 99:1 - 70:30, preferably 99:1 - 85:15 and more preferably 97:3 - 87:13, based on mass.

[0066] The thickness of the light-emitting layer can be adjusted to optimize the light-emitting efficiency and driving voltage. The preferred thickness range is 5 nm to 50 nm, more preferably 10 - 50 nm, and even more preferably 15 - 30 nm, but the thickness is not limited to this range.

[0067] In the present invention, the electron transport region may sequentially include, from bottom to top, a hole blocking layer, an electron transport layer, and an electron injection layer disposed on the light-emitting layer, but is not limited thereto.

[0068] The hole blocking layer is a layer that blocks holes injected from the anode from passing through the light-emitting layer and entering the cathode, thereby extending the lifetime of the device and improving the performance of the device. The hole blocking layer of the present invention can be disposed on the light-emitting layer. As the hole blocking layer material of the organic electroluminescent device of the present invention, compounds known in the prior art having a hole blocking effect can be used, for example, phenanthroline derivatives such as bathocuproine (referred to as BCP), metal complexes of hydroxyquinoline derivatives such as aluminum(III) bis(2-methyl-8-quinolinolato)-4-phenylphenolate (BAlq), various rare earth complexes, oxazole derivatives, triazole derivatives, pyridine derivatives, pyrimidine derivatives such as 9,9'-(5-(6-([1,1'-biphenyl]-4-yl)-2-phenylpyrimidin-4-yl)-1,3-phenylene)bis(9H-carbazole) (CAS No.: 1345338-69-3), etc. The thickness of the hole blocking layer of the present invention can be 2 - 200 nm, preferably 5 - 150 nm, and more preferably 10 - 100 nm, but the thickness is not limited to this range.

[0069] The electron transport layer can be disposed on the light-emitting layer or (if present) the hole blocking layer. The electron transport layer material is a material that easily receives electrons from the cathode and transfers the received electrons to the light-emitting layer. A material with a high electron mobility is preferred. As the electron transport layer material of the organic electroluminescent device of the present invention, electron transport layer materials known in the prior art for organic electroluminescent devices can be used, for example, metal complexes of hydroxyquinoline derivatives represented by Alq3, BAlq, and Liq, various rare earth metal complexes, triazole derivatives, pyridine derivatives such as 2,4-bis(9,9-dimethyl-9H-fluoren-2-yl)-6-(naphthalen-2-yl)-1,3,5-triazine (CAS No.: 1459162-51-6), imidazole derivatives such as 2-(4-(9,10-bis(naphthalen-2-yl)anthracen-2-yl)phenyl)-1-phenyl-1H-benzo[d]imidazole (CAS No.: 561064-11-7, commonly known as LG201), oxadiazole derivatives, thiadiazole derivatives, carbodiimide derivatives, quinoxaline derivatives, phenanthroline derivatives, silicon-based compound derivatives, etc. The thickness of the electron transport layer of the present invention can be 10 - 80 nm, preferably 20 - 60 nm, and more preferably 25 - 45 nm, but the thickness is not limited to this range.

[0070] The electron injection layer can be disposed above the electron transport layer. The material of the electron injection layer is generally preferably a material having a low work function, so that electrons can be easily injected into the organic functional material layer. As the material of the electron injection layer of the organic electroluminescent device of the present invention, the materials known in the prior art for the electron injection layer of the organic electroluminescent device can be used, for example, lithium; lithium salts such as lithium 8-hydroxyquinoline, lithium fluoride, lithium carbonate or lithium azide; or cesium salts, cesium fluoride, cesium carbonate or cesium azide. The thickness of the electron injection layer of the present invention can be 0.1-5 nm, preferably 0.5-3 nm and more preferably 0.8-1.5 nm, but the thickness is not limited to this range.

[0071] The second electrode can be disposed above the electron transport region. The second electrode can be a cathode. The second electrode can be a transmissive electrode, a semi-transmissive electrode or a reflective electrode. When the second electrode is a transmissive electrode, the second electrode can include, for example, Li, Yb, Ca, LiF / Ca, LiF / Al, Al, Mg, BaF, Ba, Ag or a compound or mixture thereof; when the second electrode is a semi-transmissive electrode or a reflective electrode, the second electrode can include Ag, Mg, Yb, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF / Ca, LiF / Al, Mo, Ti or a compound or mixture thereof, but is not limited thereto. The thickness of the cathode depends on the material used and is generally 10-50 nm, preferably 15-20 nm.

[0072] The organic electroluminescent device of the present invention may further include a packaging structure. The packaging structure can be a protective structure for preventing external substances such as moisture and oxygen from entering the organic layer of the organic electroluminescent device. The packaging structure can be, for example, a can, such as a glass can or a metal can; or a thin film covering the entire surface of the organic layer.

[0073] A method for preparing the organic electroluminescent device of the present invention includes successively laminating an anode, a hole injection layer, a hole transport layer, an electron blocking layer, an organic film layer, an electron transport layer, an electron injection layer and a cathode, and optionally a covering layer on a substrate. In this regard, methods such as vacuum deposition, vacuum evaporation, spin coating, casting, LB method, inkjet printing, laser printing or LITI can be used, but are not limited thereto. In the present invention, the vacuum evaporation method is preferably used to form each layer. Those skilled in the art can conventionally select various process conditions in the vacuum evaporation method according to actual needs.

[0074] The following examples are intended to better explain the present invention, but the scope of the present invention is not limited thereto.

[0075] The raw materials involved in the synthesis examples of the present invention can all be purchased from the market or prepared by conventional preparation methods in the art;

[0076] Example 1:

[0077] Preparation of Compound 1

[0078]

[0079]

[0080] Raw material A1 (1.4 mmol), K2CO3 (3.38 mmol), Pd(OAc)2 (0.0405 mmol) and Pcy3 (0.12 mmol) were added to a two-necked flask, which was evacuated and purged with nitrogen three times. Raw material B1 (3.0 mmol), 2-ethylhexanoic acid (0.135 mmol) and xylene (10 mL) were added to the reaction mixture, and it was stirred at room temperature for 15 minutes and then heated to 140 °C. After stirring for 18 hours, the reaction mixture was cooled to room temperature, diluted with CHCl3 (10 mL) and water (10 mL), filtered through a diatomaceous earth pad, then washed with CHCl3, the aqueous layer was separated, and it was extracted with CHCl3 (20 mL). The combined organic layers were washed with brine and dried over anhydrous magnesium sulfate to obtain Intermediate 1. LC-MS (m / z): Theoretical value: 479.10, Measured value: 480.14 ([M+H] + )

[0081] Intermediate 1 (1.0 mmol), K2CO3 (4.0 mmol), raw material C1 (3.20 mmol) and DMF (10 ml) were added to a three-necked flask, and then heated to 120 °C. After stirring for 2 hours, the reaction mixture was cooled to room temperature, the reaction mixture was poured into a large amount of MeOH to produce a precipitate. After filtration, the obtained solid was washed with MeOH, and the mixture was purified by silica gel column chromatography using hexane / chloroform as the eluent to obtain Compound 193. Elemental analysis structure (C 63 H 36 N8O) Theoretical value: C, 82.16; H, 3.94; N, 12.17; Test value: C, 82.15; H, 3.98; N, 12.16. LC-MS (m / z): Theoretical value: 920.30, Measured value: 921.33 ([M+H] + )

[0082] The preparation methods of Examples 2 - 7 were similar to that of Example 1, except that the raw materials A and B used were different. The following table lists the structural formulas of raw materials A, B, intermediates and products.

[0083] Table 1

[0084]

[0085]

[0086]

[0087] The compounds of the present invention can be used in light-emitting devices and can be used as light-emitting layer materials. The physical and chemical properties of the compounds prepared in the above embodiments of the present invention were tested, and the test results are shown in Table 2:

[0088] Table 2

[0089] Compound HOMO (eV) △Est (eV) τ (μs) PLQY (%) 193 5.81 0.15 2.51 79.5 197 5.75 0.10 2.35 84.1 225 5.79 0.08 2.07 74.7 246 5.83 0.17 1.98 83.4 267 5.97 0.11 1.79 79.5 313 5.86 0.13 2.06 80.8 315 5.88 0.09 1.92 84.7 ref-1 6.11 0.15 3.15 61.3 ref-2 6.05 0.13 2.12 26.5 ref-3 6.03 0.31 7.65 34.6

[0090] Note: HOMO: Highest Occupied Molecular Orbital energy level; △Est: Singlet - Triplet energy level difference; τ: Transient fluorescence lifetime; PLQY: Fluorescence quantum yield; The singlet energy level S1 and triplet energy level T1 were tested by a Horiba Fluorolog - 3 series fluorescence spectrometer. The test conditions for the material were a toluene solution of 2*10 -5 mol / L, △Est = S1 - T1; The highest occupied molecular orbital HOMO energy level was tested by an ionization energy test system (IPS - 3), and the test was carried out in an atmospheric environment; PLQY and τ were tested by a Horiba Fluorolog - 3 series fluorescence spectrometer.

[0091] From the data in the above table, it can be seen that the organic compounds of the present invention have appropriate energy levels, and at the same time have a short delayed fluorescence lifetime and a high fluorescence quantum yield, and can be used as a host in the light-emitting layer of OLED devices, so as to obtain OLED devices with high efficiency and long life.

[0092] The application effects of the synthesized OLED materials of the present invention in devices are described in detail below through Device Examples 1 - 7 and Device Comparative Examples 1 - 3. The manufacturing processes of Device Examples 1 - 7 and Device Comparative Examples 2 - 3 of the present invention are exactly the same as those of Device Comparative Example 1, and the same substrate materials and electrode materials are used, and the film thicknesses of the electrode materials are also kept consistent. The difference is that the light-emitting layer materials in the devices are replaced. The layer structures and test results of each device example are shown in Table 3 and Table 4 respectively.

[0093] Device Comparative Example 1

[0094] As Figure 1As shown, the transparent substrate layer 1 is a transparent PI film. The ITO anode layer 2 (with a film thickness of 150 nm) is washed, that is, washed successively with a cleaning agent (Semiclean M-L20), pure water, and then dried, and then washed with ultraviolet-ozone to remove organic residues on the surface of the transparent ITO. On the ITO anode layer 2 after the above washing, using a vacuum evaporation device, HT-1 and HI-1 with a film thickness of 10 nm are evaporated as the hole injection layer 3, and the mass ratio of HT-1 and HI-1 is 97:3. Then, HT-1 with a thickness of 60 nm is evaporated as the hole transport layer 4. Subsequently, EB-1 with a thickness of 30 nm is evaporated as the electron blocking layer 5. After the evaporation of the above electron blocking material is completed, the light-emitting layer 6 of the OLED light-emitting device is fabricated. CBP is used as the first host, ref-1 is used as the second host, and GD-1 is used as the green light doping material. The mass ratio of CBP, ref-1, and GD-1 is 67:30:3, and the film thickness of the light-emitting layer is 30 nm. After the above light-emitting layer 6, HB-1 is continuously vacuum-evaporated with a film thickness of 5 nm, and this layer is the hole blocking layer 7. After the above hole blocking layer 7, ET-1 and Liq are continuously vacuum-evaporated, and the mass ratio of ET-1 and Liq is 1:1, with a film thickness of 30 nm, and this layer is the electron transport layer 8. On the electron transport layer 8, a LiF layer with a film thickness of 1 nm is fabricated through a vacuum evaporation device, and this layer is the electron injection layer 9. On the electron injection layer 9, a Mg:Ag electrode layer with a film thickness of 80 nm is fabricated through a vacuum evaporation device, and the mass ratio of Mg and Ag is 1:9, and this layer is used as the cathode layer 10.

[0095] Device Comparative Examples 2-3 and Device Examples 1-7 were prepared in the same manner.

[0096] The molecular structural formulas of the related materials are as follows:

[0097]

[0098] After completing the OLED light-emitting device as described above, the anode and cathode are connected with a known driving circuit, and the current efficiency, voltage, and lifetime of the device are measured. The device examples and comparative examples prepared in the same manner are shown in Table 3; the test results of the current efficiency, voltage, and lifetime of the obtained devices are shown in Table 4.

[0099] Table 3

[0100]

[0101]

[0102] Table 4

[0103] Device Voltage (V) Current efficiency (cd / A) LT95 lifetime (H) Comparative Example 1 4.56 33.4 95.6 Comparative Example 2 5.23 28.7 55.4 Comparative Example 3 5.53 9.4 87.3 Example 1 4.53 43.8 178.6 Example 2 4.10 41.8 187.6 Example 3 4.46 40.9 191.5 Example 4 4.30 49.4 169.4 Example 5 4.82 40.1 166.2 Example 6 4.64 42.3 183.2 Example 7 4.72 48.7 142.9

[0104] Note: The current efficiency and voltage were tested using an IVL (current-voltage-luminance) test system (Suzhou FushiDa Scientific Instrument Co., Ltd.); the lifetime test system is the EAS-62C OLED device lifetime tester of System Technology Research Co., Ltd. of Japan; LT95 refers to the time taken for the device luminance to decay to 95%; all data were tested at 10 mA / cm 2 under the condition.

[0105] Compared with Comparative Examples 1-3 of the device, the OLED light-emitting device using the compound of the present invention as the light-emitting layer material has a greater improvement in device efficiency and device lifetime compared to the OLED device using known materials, has unexpected application effects, and has good industrialization prospects.

[0106] In summary, the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A compound with cyanopyridine as the core, characterized in that, The structure of the said compound is shown in general formula (1): In general formula (1), one of R1-R5 represents a cyano group, three of them, which are the same or different, represent substituted or unsubstituted carbazolyl groups, and one represents a substituted or unsubstituted C6-C 30 aryl group, substituted or unsubstituted C3-C 30 heteroaryl group; and among R1-R5, exactly three of them, which are the same or different, represent substituted or unsubstituted carbazolyl groups; The substituted or unsubstituted C6-C 30 The aryl is one of a substituted or unsubstituted phenyl, a substituted or unsubstituted biphenyl, and a substituted or unsubstituted naphthyl; The substituted or unsubstituted C3-C 30 heteroaryl is one of a substituted or unsubstituted quinazolinyl, a substituted or unsubstituted triazinyl, and a substituted or unsubstituted dibenzofuranyl; The substituents for the substitution groups are each independently selected from one or more of a deuterium atom, a cyano group, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tert-butyl group, a phenyl group, a biphenyl group, a naphthyl group, a dibenzofuran group, and a carbazolyl group.

2. The compound with cyanopyridine as the core according to claim 1, characterized in that, R2 is represented as a cyano group, and R3 is represented as a substituted or unsubstituted C6-C 30 aryl group, a substituted or unsubstituted C3-C 30 heteroaryl group, and R1, R4, and R5 are each independently the same or different and are represented as a substituted or unsubstituted carbazolyl group; alternatively, R2 is represented as a cyano group, and R1 is represented as a substituted or unsubstituted C6-C 30 aryl group, a substituted or unsubstituted C3-C 30 heteroaryl group, and R3, R4, and R5 are the same or different and are represented as a substituted or unsubstituted carbazolyl group; The substituted or unsubstituted C6-C 30 aryl is one of a substituted or unsubstituted phenyl, a substituted or unsubstituted biphenyl, and a substituted or unsubstituted naphthyl; The substituted or unsubstituted C3-C 30 heteroaryl is one of a substituted or unsubstituted quinazolinyl, a substituted or unsubstituted triazinyl, and a substituted or unsubstituted dibenzofuranyl; The substituents for the substitution groups are each independently selected from one or more of a deuterium atom, a cyano group, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tert-butyl group, a phenyl group, a biphenyl group, a naphthyl group, a dibenzofuran group, and a carbazolyl group.

3. The compound with cyanopyridine as the core according to claim 1, characterized in that, R1 is represented as a cyano group, and R2 is represented as a substituted or unsubstituted C6-C 30 aryl group, a substituted or unsubstituted C3-C 30 heteroaryl group, and R3, R4, and R5 are each independently the same or different and are represented as a substituted or unsubstituted carbazolyl group; or, R1 is represented as a cyano group, and R3 is represented as a substituted or unsubstituted C6-C 30 aryl group, a substituted or unsubstituted C3-C 30 heteroaryl group, and R2, R4, and R5 are each independently the same or different and are represented as a substituted or unsubstituted carbazolyl group; The substituted or unsubstituted C6-C 30 aryl is one of a substituted or unsubstituted phenyl, a substituted or unsubstituted biphenyl, and a substituted or unsubstituted naphthyl; The substituted or unsubstituted C3-C 30 heteroaryl is one of a substituted or unsubstituted quinazolinyl, a substituted or unsubstituted triazinyl, and a substituted or unsubstituted dibenzofuranyl; The substituents for the substitution groups are each independently selected from one or more of a deuterium atom, a cyano group, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tert-butyl group, a phenyl group, a biphenyl group, a naphthyl group, a dibenzofuran group, and a carbazolyl group.

4. The compound with cyanopyridine as the core according to claim 1, characterized in that, The R3 is represented as a cyano group, and the R1 is represented as a substituted or unsubstituted C6-C 30 aryl group, a substituted or unsubstituted C3-C 30 heteroaryl group, and R2, R4, and R5 are each independently the same or different and are represented as a substituted or unsubstituted carbazolyl group; alternatively, the R3 is represented as a cyano group, and the R2 is represented as a substituted or unsubstituted C6-C 30 aryl group, a substituted or unsubstituted C3-C 30 heteroaryl group, and R1, R4, and R5 are each independently the same or different and are represented as a substituted or unsubstituted carbazolyl group; The substituted or unsubstituted C6-C 30 aryl is one of a substituted or unsubstituted phenyl, a substituted or unsubstituted biphenyl, and a substituted or unsubstituted naphthyl; The substituted or unsubstituted C3-C 30 heteroaryl is one of a substituted or unsubstituted quinazolinyl, a substituted or unsubstituted triazinyl, and a substituted or unsubstituted dibenzofuranyl; The substituents for the substitution groups are each independently selected from one or more of a deuterium atom, a cyano group, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tert-butyl group, a phenyl group, a biphenyl group, a naphthyl group, a dibenzofuran group, and a carbazolyl group.

5. The compound with cyanopyridine as the core according to claim 1, characterized in that, The specific structure of the said compound is any one of the following structures:

6. An organic electroluminescent device, comprising an anode and a cathode, and an organic light-emitting functional layer therebetween, the organic light-emitting functional layer including a light-emitting layer, the light-emitting layer containing a first host material, a second host material and a doping material, characterized in that, The first host material is a TADF material, and the second host material is the compound with a cyanopyridine core as described in any one of claims 1-5.

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